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[Bug c++/53707] compiler generates wrong code
- From: "mikpe at it dot uu.se" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 02 Jul 2012 20:00:34 +0000
- Subject: [Bug c++/53707] compiler generates wrong code
- Auto-submitted: auto-generated
- References: <bug-53707-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53707
Mikael Pettersson <mikpe at it dot uu.se> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mikpe at it dot uu.se
--- Comment #12 from Mikael Pettersson <mikpe at it dot uu.se> 2012-07-02 20:00:34 UTC ---
(In reply to comment #11)
> OK, I don't know if it's related, but
> https://bugs.gentoo.org/show_bug.cgi?id=424475
> and its follow-up
> http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11845
>
> This code:
> int
> find_stack_direction ()
> {
> static char *addr = 0;
> auto char dummy;
> if (addr == 0)
> {
> addr = &dummy;
> return find_stack_direction ();
> }
> else
> return (&dummy > addr) ? 1 : -1;
> }
>
> int
> main ()
> {
> return find_stack_direction () < 0;
> }
>
> works with '-O2' and gcc 4.6.3, breaks on the same compiler with '-O3'
> works with both '-O2' and '-O3' on 4.7.1.
>
> On an interesting note, it works with both '-O2' and '-O3' on 4.5.3 too.
This one is not a C++ issue. Please move it to a new PR. I can reproduce it
with 4.6-20120629 on x86_64-linux, but not with 4.7-20120630 or 4.8-20120701.